Casting Life Drain

How do I make my casters cast life drain through a trigger? It wouldn't cast it when I used "Order Unit to Neutral Dark Ranger - Life Drain TagetUnit"...

hah, now you are having the same problem as me, this proves the WE is ineffective in ording units to cast spells

I'm thinking the problem is that Life Drain doesn't have an order string... Most spells do like Earthquake's is 'earthquake' but this spell doesn't. Or at least the WE doesn't show it.